Centrifugal clutch and vacuum converter



' April 22, 1941. E. E. WEMP CENTRIFUGAL CLUTCH AND VACUUM CONVERTERFiled May 25, 1935 I 5 Sheets-Sheet l Q 1N VENTOR. I

. ATTO EYJ.

imlllll April 22, 1941. E. E. wr-:MP 2,239,163

ATTORNEY.

April l2z, 1941. E. awr-:Misl 2,239,163

I CENTRIFUGAL CLUTCH AND VACUUM CONVERTER I Filed May 25, 1935 15Sheets-Sheet 5 l, QQ INVENTOR.'

ERA/EJ T5 Wan/O.

ATTORNEYS,

fidi/M April 22, 1941. E, E WEMP A 2,239,163

CENTRIFUCAL CLUTCH AND'VACUUM CONVERTER Filed may 25, 1955 f 5sheets-sheet 4V io A INVENTOR.

y ERA/55 7E. WEMP- ATTORNEY5- April 22, 1941.- E, E, WEMP 2,239,163

CENTRIFUCAL CLUTCH AND VACUUM CONVERTER Filed nay 25, 19:53 5sheets-sheet 5 WVENTOR.v

A Ema/H5 TE. Wann Patented Apr. 22, 1941 CENTRIFUGAL CLUTCH-AND VACUUMCONV EETEB FFiCE.

Ernest E. Wemp, Detroit, Mich.

Application May 25, 1933*, Serial No. 672,794

19 Claims. (Cl. 192-105) This invention relates to centrifugal clutches,and it is concerned particularly with a combination embodying acentrifugal clutch and-clutch actuating means for converting the sameinto a clutch of manual operation type. The invention aims to provide animproved clutch structure notwithstanding the fact the case is entitledCentrifugal clutch and vacuum converter as thistitle has been given tothe case to aid in identifying it from certain other applications. Theclutch structure itself embodies generally an arrangement such as shownin application Serial No. 672,793, filed May 25, 1933, now Patent No.2,044,487 of June 16, 1936, with improvements in. certain structuralparts. In my application Serial No. 607,064, led April 23, 1932, acentrifugal clutch is shown wherein an automatically acting mechanicalcontrivance is provided for converting the centrifugal clutch into amanual clutch when the parts cease rotating. The present invention isdirected toward the provision of certain improvements in a. conversionsystem, which improvements generally reside in the provision of clutchconversion means controlled by differential pressures. To this end thepartial vacuum or depression in the engine intake manifold may beutilized for the purpose of actuating the clutch converter mechanism.

The centrifugal clutch is one preferably designed to be disengaged atthe normal idling speed of an internal combustion engine. This usuallyis from 400 to 500 R. l?. M.. When the engine is accelerated, the clutchengages. The centrifugal clutch would ordinarily remain disengaged whenthe engine is stopped so that when an automotive vehicle is leftstanding the clutch would be open. However, the converter system forminga part of the present invention causes the clutch to become engagedsubstantially as the internal combustion engine comes to a stop, and infact may be, what is termed herein, converted into a manual type ofclutch. Moreover, the invention contemplates the combination embodying acentrifugal clutch and a vacuum controlled mechanism, working inconjunction therewith, by means of which an improved clutch; action isobtained, and a clutch having centrifugal ele- .ments of relativelylight weight can be used.

This will be brought out more in detail as the detailed descriptionprogresses. Sumce to say at this time that under certain operatingconditions a centrifugal clutch of light construction 'may not be ableto transmit the torque; in other words, the clutch may slip. This is, ofcourse, undesirable even though it is desirable to use light clutchweights for several other reasons as will later appear. However, thevacuum converter system, which operates in accordance with a conditionin the intake manifold oi the engine, acts upon the clutch in such a Wayas to prevent such slippage.v

Fig. 1 is a view partly in section, illustrating a clutch and vacuumcylinder arrangement con-v structed in accordance with the inventionshowing the same in engine idling condition with the clutch disengaged.

Fig. 2 is a. similar. view showing the parts in at rest position withthe clutch engaged.

Fig. 3V is a similar view showing the parts in normal operatingcondition with the clutch en gaged.-

Fig. 4 is a view of the clutch partly in rear elevation and with partscut away showing some of the interior construction. I

Fig. 5 is an enlarged sectional view taken substantially on line 5 5 ofFig. 4 showing the f clutch packing spring arrangement.

Fig. 6 is an enlarged detail view showing the normal operating means forthe clutch.

Fig. 7 is a general view illustrating an internal combustion engine andgeneral environment for the clutch.

Fig. 8 is'a view in side elevation showing a clutch control lever andmounting which may be used.

Fig. 9 is an enlarged view looking substantially in the direction ofarrows Q- of Fig. 3.

Fig. 10 is a view looking substantially on line iii- I0 of Fig. 8.

Referring first to Fig. 7: An internal combustion engine is shown at i,a clutch housing at 2, the usual transmission case at 3, and a vehicledriving shaft at d. The clutch arrangement of 'the present inventionvmay most advantageously be employed with 'a free wheeling unit whichmay be disposed between the transmission 3 and shaft 4 as, for example,at 5. These free wheeling units are weil-known, and may take any one ofvarious structural forms,.and they provide a oneway driving action sothat the shaft i may over- .run the engine.

The clutch structure is inside the housing 2 and, as shown in Fig. 1,may have one driving member i0 which may be a flywheel equipped with ausual clutch cover plate il. 'I'he clutch structure is confined in thecover plate and it is desirable that the structure be compact and thepresent invention makes it feasible to use a clutch cover il ofsubstantially the same dimensions as clutch covers conventionally in usetodayl notwithstanding the fact that the centrifugal clutch embodies anumber of additional elements including, centrifugal weights, etc. Aclutch driving member, in the form of a pressure ring, is shown at I2,and it may have projections I3 lying in slots I4 of the cover plate fordriving purposes. A clutch driven disc is shown at I5, the

hub of which is mounted upon a driven shaft I6 drivin relationtherewith. A back plate of arnnular gorm,` as at I1, is mounted withinthe cover and it may be piloted by the pressure ring as at I8, and thisback plate is acted upon by a series of packing springs I9 (Fig. 5)reacting against the cover and the bottom of cups 20 carried by the backplate. Studs 2| are taken in the pressure ring l2 each of which projectstelescopically into the cup 20 and spring I9, and a retracting spring 22may be associated withA each stud and acts against the packing spring|9, but-cf course, is of much less strength. 'I'he springs are arrangedas illustrated in Fig. 4. The back plate also carries radially shiftablecentrifugal weights 25 which stop inwardly against brackets 26 andoutwardly against the peripheral portion of the back-plate. The brackets2.6 are secured to the back plate, and the centrifugal weights arebacked up preferably by anti-friction bearings 21, and co-act with thepressure ring by inclined surface means which may comprise a ball 28pocketed in recesses with inclined surfaces as shown. The springs 22, inretracting the pressure ring, exert a force through the balls 28 and theinclined planes to hold the weights inwardly against the stops 26 asshown in Fig. 1.

The cover plate carries studs 30, the inner ends of which may besupported slidably by fitting into bushings 3| in the pressure ring, andon these studs clutch operating levers 33 are mounted.` to rock on anaxis as at 34, and an anti-ratthng spring 35 may be associated with eachlever. The levers may fulcrum against fulcrum blocks 36 backed up by theback plate. The several centrifugal weights are preferably each providedwith a rubber bumper 31 for stopping against the bracket 26, and withrubber bumpers 38 (Fig. 4) for stopping against the peripheral flange ofthe back plate |1. Preferably also the bearings 21 are three in numberto provide a three-point backing for each weight as shown in Fig. 4;preferably the clutch operating levers are three in number; andpreferably the weights are three in r each having a single co-actingcontact gvil'ltrllibtie pressure ring through the means of the ball 28.The clutch, as thus far described, save for an arrangement of themounting of the back plate and the driving arrangement for the backplate, is the same in principle as the clutch covered in my applicationSerial No. 672,'793.

Aside from other instrumentalities having a bearing on the clutch itoperates as follows: At normal engine idling speed, the centrifugalweights 25 are positioned substantially as illustrated in Fig. 1 and theclutch is open. Upon acceleration the weights 25 move outwardly to aposition as illustrated in Fig. 3 and through the means of the balls 28and the wedging surfaces, the pressure ring I2 is forced up against thedriven disc and the driven disc is packed between the ywheel and thepressure ring. This movement of the weights forces the back plate awayfrom the pressure ring and toward the cover plate and against thecompressing action of the clutch packing springs I9. When the partsagain reach idling speed the clutch will automatically disengage withthe parts assuming the position as illustrated in Fig. 1.

'Ihe next item to be considered, as regards the operation of the clutch,is that when the engine is brought to complete stop, the partsautomatically take the position as illustrated in Fig. 2 and the clutchis again engaged so that a vehicle may be left in gear with the engineserving as a braking agency, and so that power may be transmitted fromthe traction wheels to the engine where it is desirable or necessary tostart the engine by vehicle movement. It will be apparent that thelevers 33 rock as the back plate I1 shifts axially. 'Ihe clutch packingsprings are tending, at all times, to shift the back plate toward thepressure ring, thus tending to rock the lever 33 (Fig. 1)counterclockwise. This would engage the clutch, but a clutch throw-outmember 40 stops the levers, thus holding the clutch disengaged in theFig. 1 position. When the clutch is engaged the inner ends of the leversrock toward the pressure ring as illustrated by the dotted-line andfull-line positions in Fig. 3. Means are provided for keeping thethrow-out bearing 40 up against the throw-out levers so that as thelevers shift in clutch engagement and dis/engagement the throw-outbearing follows the same and maintains a contact therewith.

A clutch throw-out lever is illustrated at 4| and it is preferred that aspecial form of lever arrangement be used with the clutch structure.This arrangement may be of the type as shown in my Patent No. 1,830,306of November 3,'1931, wherein the lever and the rock shaft for operatingthe clutch are disconnected when the clutch engages and the leverretracts to normal position. This permits of movement of the clutch rockshaft independently of the foot lever. The foot lever arrangement shownherein is an improvement over that shown in the patent and is covered ina'separate patent application. The usual rock shaft is shown at 42, andit is lprovided with a yoke 39 which acts upon the clutch throwoutbearing 40. Keyed to the rock shaft ls a serrated segment member 43. Thelever 4| is pivoted as at 44, which may be termed a. knee joint, on alever section 45 pivotally mounted upon the shaft 42 and having a heel46 adapted to abut a suitable stop 41. The lever 4| has a heel 48, and acoil spring 49 which is a tension spring, as shown, connects the heel 48and hooks around a suitable bracket or part 50. The lever 4| has aserrated shoe 5|, and a finger 52 arranged to contact with a, part ofthe lever section 45. .'When the lever 4| is at rest, it is retractedagainst the oor boards as illustrated in Fig. 8, or other suitable stopby the spring 49. y'I'lie spring 49 tends to rock the lever 4| aroundthe knee joint 44, and the finger 52 contacts with the part 45. 'I'heresult is that the spring 49 holds the heel 46 against the stop 41. Withthe parts in these positions the serrated shoe 5| and the serratedsegment 43 are separated as shown in Fig. 1. Accordingly, the rock shaft42 may actuate Without movement of the lever 4|. An operator may depressthe pedal 4|, andthe pedal 'first fulcrums around the point 44. 'Theproportions of the parts and the spring tension on the lever 4| and thekeyed part 45 must be such that the turning moment which the spring 49exerts on the member 45 in a clockwise direction, as

Fig. 1 is viewed, is greater than the turning moment exerted on themember 45 when the lever 4| is depressed in order to break the kneejoint 44. The result is that the lever moves through a certain amountoflash movement, to a position illustrated by the dotted lines in Fig. 8and the shoe El moves into engagement with the serrated segment 43, andthence `further movement of the lever moves th segment 43 and shaft 42.As mentioned above, this particular arrangement is covered in moredetail in another application.

A vacuum motor is shown at E having a diaphragm 5t of rubber or the liketo which is connected a rod El closed by a rubber dust sealing element58, and a vacuum line 53 connects the motor to the intake manifold ofthe engine es shown in Fig. 7. The head of the vacuum motor may have asheet metal head 6@ provided with a suitable numberl of apertures 3iover which is secured a flexible disc 52 of rubber or the like, f

and a bleeder port t3 clear of the rubber disc may be provided. Vacuumcreated in the manifold shifts the diaphragm and rod 5l to a position asillustrated in Figs. 1 and 3 and, in the absence of a dierentialpressure, the diaphragm and rod may shiftto a position as illustrated inFig. 2. The vacuum motor is, in the present structure, open to theatmosphere on theside of the diaphragm opposite the vacuum line 59. Thismay be accomplished by the provision of one or more apertures (notshown) in the rubber dust sealing element 33.

Connected to the rod 5l is an arm t5 having a projecting part to, andthis arm may be pivotv ally mounted upon the clutch controlv rock shaftAn arm tl has a hub part 68 keyed to the shaft 42 and it may have anadjustable screw stop 69 for contact with the projection 66. A spring'l0 of fairly light construction and action exerts a torque action uponthe arm Si, and a suitable stop H may be provided for limitingthemovement ofthe arm 67 and rock shaft 63.

Brieiiy reiterating the structure .centering on the rock shaft, it willbe noted that the manual control comprises the serrated segment 43 keyedto the shaft, and the lever part 45 rockable on the shaft in addition tothe lever 4I. These parts are usually on the shafton one side of theengine. However, Figs. 1, 2, and 3, inzorder to be complete, have alsoshown the parts associated with the vacuum motor. These parts lwhich areassociated with the vacuum motor comprise the link 65 pivoted on therock shaft and having the projection 66, and the arm 61 keyed to theshaft. The cooperating parts 65 and 51 are advantageously, in a.commercial structure, mounted upon the shaft on the opposite side of theengine.

The operation will be rendered clear, it is believed, by keeping in mindthat cooperating parts 65 and 61 on the one hand are entirelydis-associated from the lever parts 43 and 45 except through theirmounting upon the shaft 42.

Considering now'the operation: Assume that the engine is idling-theparts will be in a position shown in Fig. 1, with the clutch disengageddue to the fact that the centrifugal weights are inoperative, and due tothe fact that the depression or partial vacuum in the manifold of theengine has shifted the diaphragm to the position shown. This holds thearm 65 solidly with the projection 66 backing up the member 31, which iskeyed to the rock shaft, with the result that the yoke 39 holds thethrow-out memberl I0 in the position shown. The clutch throw-out leverstion shown in Fig. 3 thus engaging the clutch and backing' away the backplate i1,thus com pressing the packing springs i3. In this action theback plate shifts the clutch throw-out levers from the dotted-lineposition to the full-line position shown in Fig. 3. The clutch throw-outbearing 40 follows up the levers and this may be caused bythe coilspring "I3 pulling on VVthe arm 3l and rocking theshaft 42. This pullsthe stop 39 away from .the projection 6B asillustrated in Fig. 3. Alsoit shifts the serrated segment as will be noted by -a comparison ofFigs. 1 and 3.

If the engine be again brought down to idling speed, the centrifugalweights shift back to the Fig. l position, the pacmng springs shift theback plate towards the `left as the figures are 'viewed and the levers33 push the throw-outl member e0 to the right tensioning the spring loand shifting the rock shaft, arm Si, and serrated segment 43, all backto the Fig. 1 position.

Now suppose that the engine is brought to a stopvas by turning ofi theignition: The depression in the va-cuum motor is released and a bleedingaction takes place through the .bleeder port 63 so that the diaphragm nolonger holds the link G5 and its projection 36 ina position to preventclockwise rotation of the shaft 42. Accordingly, the clutch packingsprings shift the back pla-te ii and pressure ring to the left to engagethe clutch as shown in Fig. 2, in which action',1 the levers 33 rockfrom the dotted-line position to the full-line position backing away thethrow-out member. This. of course, also rocks the shaft l42, theserrated segment 43, and the arm 61.

Thus, it will be noted that there are at least three major positionswhich the clutch throwout levers 33 may take in the automatic action ofthe clutch and that the clutch throw-out member 40 andthe levers are atall times substantially in contact with each other. When the .l

'engagethe clutch just like the ordinary clutch of today. It will beapparent that the clutch may be disengaged at anytime by manualoperation of the lever 4I'. While the segment 43 -has shifted fromposition to position, yet the lever 4| has remained stationary and thelash movement is constan-t at any time. By pressing the lever 4i itmoves through a lash movement until its shoe 5i grips the segment 43 andthen continued` movement of the lever retracts the back plate, thecentrifugal weights, and pressure ring bodily without overcomingcentrifugal force. This-action may take place during the-at restposition or during the operation and engaged position, and since thethrow-out `member 40 follows the levers disengagement of the clutchstarts as soon as'the'shoe 5l grips the segment 43. This provides for amaximum range of lever movement in releasing the clutch. 'Inasmuch asthe parts are housed in a small clutch cover there is the possibilitythat an operator would depress the pedal too far so as to cause thelevers to jam against some of the clutch parts near the hub and for thispurpose the stop 1I is provided to limit the rocking movement of theshaft 42 by 33 back up against. the throw-out member and are impededfrom further movement.

Now assume that the engine is accelerated:

The centrifugal weights may shift to the posiphysical effort of theoperator.'

'Ihe vacuum control mechanism or vacuum converter system, as it may betermed, has another important and automatic function during 4 vehicleoperation and this function permits of use of light weights in thecentrifugal clutch. The use of light weights is desirable to save spaceand also to provide for a nicety of clutch engagement when getting thevehicle under way in low gear, at which time the engine is rotating at arelatively high R. P. M. and there is a chance for a too rapid clutchengaging action. The light weights minimize this chance. However, thereare conditions where the engine is 'operating under full torque but theR. P. M. is not high. This may occur when the engine is under heavy loadin high gear, and one example may be visualized in a long hard up-hillpull with the l vehicle materially decelerated. Under such conditions asthese, a centrifugal clutch may slip because the centrifugal action isreduced by the low R. P. M., yet the torque is high. Generally, however,where such conditions arise, the depression in the intake manifold islow because the engine is Working on a wide open throttle, orsubstantially a wide open throttle. This means that pressure in themanifold begins'to approach atmospheric pressure. Accordingly, thediaphragm in the vacuum motor may no longer be held in the Fig. 1position and may start shifting back to the Fig. 2 position. When thisoccurs, the entire assembly, including the back plate, pressure ring andintermediate weights, shift forward under action of the clutch packingsprings and the clutch becomes engaged even though the centrifugalweights are only partially effective. Under this condition, thecentrifugal weights may be in a position somewhere between the extremepositions illustrated in Figs. l and 2. Accordingly, the clutch is,automatically converted to a manual type of clutch when the torque ishigh and the R. P. M. is low. The weights of the clutch and thearrangement of the converter mechanism may be calculated to produce a.proper action or conversion. Of course, as soon as the engine picks upspeed again, the clutch automatically is convertedto a centrifugal typeand the diaphragm moves back to the Fig. 1 position.

The clutch may, for example, be fully engaged by the centrifugal weightsat a speed of from 900 to 1000 R. P. M. The manual operation of theclutch makes the use of the structure feasible under a condition whereit is necessary to keep the engine operating at an R. P. M. higher thannormal idling speed as is the case when the engine is cold. In this casethe clutchl may be manually engaged and released like the conventionalclutch at the present time. Occasionally it may be desirable to releasethe clutch at a high engine speed in order to take advantage of theflywheel inertia in jumping a car out of a hole or the like, and thismay be done manually. It is to be noted that a manual clutch releasinglever constructed to permit movement of the clutch throw-out levers andassociated parts, without lever movement, is particularly advantageousfor use in connection with the present invention. A conventional clutchpedal would have to be connected to the rock shaft so as to permit thethrow-out bearing 40 to recede to the Fig. 2 position without firstcoming against the toe boards; then on the change over from the at restposition (Fig. 2) to the idling position (Fig. 1) the clutch throw-outlevers would move away from the throw-out bearing; then on the changeover from theidling vcondition to the operating condition the clutchthrow-out levers would move still further away from the throwi inothers.

out bearing. The obvious result of this would be that an ordinary clutchlever would have to be depressed through a long range of movement inorder to bring the throw-out bearing up against the clutch levers, thusleaving only a very small, and probably, too small a range of movementto disengage the clutch manually. At any rate, the clutch could not bedisengaged with facility under these conditions. However, a lever wlthaspecially long range of movement could be used with the clutch and someof the appended claims herewith recite this arrangement irrespective ofthe type of lever used.

Moreover, the lever hook up automatically compensates Vfor Wear in theclutch facings since the clutch throw-out levers, the throw-out bearing.the rock shaft, the serrated segment and associated parts may shiftprogressively in clutch engaged condition as the facings Wear awaywithout disturbing the normal footv pedal position. This, however, iscovered more in detail in the application covering the lever structure.In some of the claims attached hereto it is specified that the vacuumconverter means is connected to the engine manifold; that the meanswhich works by differential pressure is a vacuum controlled means; thatthe releasing lever is a normally operable lever; these terms are usedfor the purpose of convenience and it is to be understood that thevacuum controlled means may be connected to any part of the engine whichwould perform an action equivalent to connecting it to the manifold,that the vacuum means may operate by a. partial vacuum and does notnecessarily have to be a means Working on a high vacuum, and that thelever for manual control may be worked by the foot of the operator, andin fact it is expected that the lever be so operated in the usualinstallation.

It is, of course, to be appreciated that different vehicles, dependingupon their power and weight largely, have clutches of varying torquecapacities. This means that moreforce is required to impede the packingsprings in some clutches than So fa'r as the present invention isconcerned different forces can be accommodated by varying the size ofthe vacuum motor, or the leverage through which it works. However, it isbelieved to be preferred to use a standard size vacuum motor largeenough to take care of a clutch of high torque capacity and throughmeans of additional elements, adapt this vacuum motor for use on smallerjobs. This may be done by adding an element, such as a spring 15', forworking against the vacuum acting upon the diaphragm.r 'I'his spring maybe` an extension spring, as shown, and may be connected to the arm andto another fixed member, such as a bracket 16, which may be providedwith a number of apertures l1.

By selecting a spring of .proper strength the effective force of thelever 65 on the clutch may be determined as desired. With a heavy dutyclutch the vacuum motor may be used without a spring, or with a springof little strength, and the same vacuum motor can be used with smallerclutches by selecting stronger springs. Instead of selecting springs,one end of the spring may be adjustably I connected into any one of theseries of apertures aasaiea l synonymous to` the term partial vacuum. Inthe present instance the depression or partial vacuum is a pressure lessthan atmospheric pressure. However, the pressures on opposite sides ofthe diaphragm may be higher or lower than atmospheric pressure, and themeaning which is intended to be conveyed by the use of the termdepression is that the pressure on one side ofthe diaphragm is reducedbelow that of the pressure on the opposite side of the diaphragm. Inother words, the pressure on one side is depressed relative to thepressure on'the opposite side, vwhether or not this be consideredtechnically a partial vacuum. The term depression is quite commonly usedin the art in this connection .and has been adopted as a convenientterm.

Some of the claims make reference to the fact that the motor or vacuumcontrol means is connected to the intake manifold. The connecting of thevacuum motor to the piping conveying the fuel to the engine (whethertechnically considered a manifold or not) to create a depression orpartial vacuum in the motor'is the full equivalent of connecting to themanifold, as specified shiftable by diierential pressure located in achamber, an open conduit constantly connecting one side of the chamberto the .intake manifold of the engine, said element being shiftable uponvariation in the depression in the engine manifold, and meansoperatively connecting the element to the clutch.

2. The combination with an internal combustion engine, of a clutchhaving driving and driven members. centrifugal means for engaging the vclutch atan R. P. M. above engine idling speed and arranged t0 releasethe clutch substantially at idling speed, means tending to engage theclutch at all times, means for impeding the engagi'ng movement includingan element shiftable by differential pressures and disposed in a cham--ber connected vto the engine intake manifold f whereby said element isheld positioned by a relatively high depression in the manifold, sothat.

the clutch is held open when the engine is idling, said element beingshiftable when the depression in the manifold is relatively low wherebyto permit engagement of the clutch under the action of said meanstending to engage the clutch to substantially offset the loss ofcentrifugal force for engaging the clutch when the engine is operatingat high torque and at a relatively-low R. P. M.

3. The combination with an internal combustion engine, of a clutchhaving driving and driven members, clutch packing springs tending toengage the clutch, vacuum controlled clutch converter mechanismoperating from the depression in the intake side of the engine forholding the clutch disengaged against the action of the packing springs,centrifugally controlled means for engaging the clutch at an R.. P. M.above normal engine idling speed and for releasing the clutchsubstantially at idling speed, said vacuum controlled convertermechanism being rendered inoperative when the engine stops whereby theclutch is substantially converted into a spring en gaged form of clutchand becomes engaged.

4. The combination with an internal combustion engine, of a clutchhaving driving and driven members, clutch packing springs tending toengage vthe clutch, vacuum controlled clutch converter mechanismoperating from the depression in the intake side of the engine forholding the clutch against the action of the packing springs,centrifugally controlled means for engaging the clutch at an R. P. M.above normal engine idling speed andl for releasing the clutchsubstantially at idling speed, said vacuum controlled convertermechanism being `coordinated with the centrifugally controlled meanswhereby, when the clutch engaging action lessens by reason of the engineoperating at a low R. P. M. and at high torque capacity, with thedepression in the intake side of the engine lowered, said convertermechanism shifts to permit the clutch to engage under the action of saidsprings, to substantially counteract the lessening of the clutchengaging action by centrifugal force.

5. The combination with an internal combustion engine, of a clutchhaving driving and driven members, centrifugal means for engaging theclutch atan R. P. M. above engine idling speed and for releasing theclutchl substantially at idling speed of the engine, and means operableby dierential pressures and acted upon by the partial vacuum created inthe intake side of the engine for holding the clutch open when theengine is idling, said means being so coordinated with the centrifugalmeans whereby, when the clutch packing action of the centrifugal meanslesens by operation of the engine at a relatively low R. P. M. and athigh engine torque, the vacuum controlled means shifts by reason of therelatively low depression in the intake side of the engine to permit ofa. clutch engaging action calculated to supplement the lessened clutchengaging action effected by centrifugal force.

6. The combination-with an internal combustion engine, of a. clutchhaving driving and driven members, clutch packing springs tending toengage the clutch, means for impeding the action of the springs, vacuumcontrolled means operating 0H the intake side of the engine for holdingthe impeding means in impeding position when the engine is idling sothat the clutch is held open, centrifugal means for engaging the clutchineffective aty engine idling" speeds and effective at'an R. P. M. aboveengine idlingspeeds, said vacuum controlled means and centrifugal meansbeing so coordinated that when'the centrifugal force for engaging theclutch lessens by engine operation at a relatively low R. P. M. and

at high torque capacity, the vacuum controlled means shifts by reason ofthe loweredv depression in the intake side of the engine to render theimpeding means ineffective.

'7. The combination with an internal combustion engine, of anautomatically acting centrifugal clutch having centrifugally controlledmembers of insumcient weight to provide requisite torque capacity whenthe engine is operating at a relatively low R. P. M. and at a hightorque, and vacuum controlled means operating o the intake side of theengine and operatively associated with the clutch and arranged to effectan increase in the clutching action' to supplement the lessened clutchaction obtained centrifugally under the conditions above mentioned.

8. The combination with an internal combustion engine, of acentrifugally controlled clutch having centrifugally shiftable membersof a weight insufficient to effect a clutching action of adequate torquecapacity when the engine is operating at a relatively low R. P. M. andunder high torque, at which time the depression in the intake side ofthe engine is relatively low, clutch packing springs, vacuum controlledmeans operating off ithe intake side of the engine and rendering theclutch packing springs ineffective when the depression is high, andarranged to render the packing springs effective when the depression inthe intake side of the engine is relatively low.

9. The combination with an internal combustion engine, of anautomatically acting centrifugal clutch having centrifugal members of aweight insuincient to provide adequate torque capacity to prevent clutchslippage when the engine is operating at a relatively low R. P. M. andat a high torque, at which time the depression in the intake side of theengine is relatively low, clutch packing springs tending to engage theclutch, vacuum controlled means operating of! the engine manifold formaintaining the springs ineffective for engaging the clutch when thedepression is relatively high and arranged to render the springseffective when the depression is relatively low, whereby the loss ofcentrifugal force under the conditions above mentioned may besupplemented by the clutch packing springs to prevent clutch slippage.

10. The combination with an internal combustion engine, of anautomatically acting centrifugal clutch having centrifugal members of aweight insumcient to provide adequate torque capacity to prevent clutchslippage when the enginevis operating at a relatively low R. P. M. andat a high torque, at which time the depression in the intake side of theengine is relatively low, clutch packing springs tending `to engage theclutch, vacuum controlled means operating on the engine manifold formaintaining the springs ineffective when the clutch is disengaged andwhen the depression is relatively high, and arranged to render thesprings effective when the depression is relatively low, whereby theloss of centrifugal force under the conditions above mentioned may besupplemented by the clutch packing springs to prevent clutch slippage, amanually controlled lever shiftable to release the clutch at any timeduring its engagement, and normally disconnected means betweenstheclutch and lever arranged to permit clutch movement independent of thelever and arranged to establish an operable connection upon initialmovement of the lever.

1l. In combination, a clutch adapted for use with an internal combustionengine and having driving and driven members, packing springs tending toengage the clutch, vacuum controlled means for holding the clutch openat engine idling speed and operating oil the intake side of the engine,centrifugally controlled means for engaging the clutch above engineidling speed and for releasing the clutch substantiallyat engine idlingspeed, clutch throw-out means shiftable as the clutch engages andreleases centrifugally, a manually controlled clutch throw-out levernormally disconnected L from the clutch throw-out means, and cooperatingelements on the clutch throw-out means and lever establishing operableconnecting between the lever and the clutch throw-out means upon initialmovement of the lever.

12. 'I'he combination with an internal combustion engine, of a drivenmember to be driven thereby, a clutch for connecting the engine and thedriven member, centrifugally controlled means mounted to rotate directlywith the engine to engage and release the clutch in accordance with thespeed of rotation of the engine, control means operating oil the fuelintake piping of the engine for acting upon the clutch, and

co-ordinated with the centrlfugally controlled means to effect a certainincrease in the clutching action upon a decrease of the clutching actionincident to the lessening oi' the centrifugal force at relatively low R.P. M. of the engine.

13. The combination with an internal combustionengine, of a drivenmember to be driven by the engine, a centrifugal clutch for establishinga connection between the engine and the driven member, said clutchhaving driving and driven members and having cntrifugally actuated meanscarried by a clutch driving member, for engaging and releasing theclutch in accordance with the speed of rotation of said clutch drivingmember, control means operable by differential pressures and operatingoft" the fuel intake Piping of the engine for acting upon the clutch,said control means being co-ordinated with the centrifugal clutch toeiect certain in,- crease in the Yclutching action upon a decrease oithe clutch action incident to the lessening of the centrifugal force atrelatively low R. P. M. of the said clutch driving member.

14. In combination with a clutch automatically engageable above apredetermined rotative speed, a suctionr clutch operator adapted topermit said clutch to engage regardless of the rotative speed andoperative to disengage said clutch at high degrees of suction when therotative speed is below the predetermined speed, and means for delayingthe movement of said suction clutch operator from its clutch disengagingposition to its inactive position whereby to provide a predetermineddelay in clutch engagement sufficient to properly pick up the load underextreme operating conditions.

15. In combination with a clutch automatically engageable above apredetermined rotative speed, a suction clutch operator adapted topermit 4said clutch to engage regardless of the rotative speed andoperative to disengage said clutch at high degrees of suction when therotative speed is below the predetermined speed, and manually operablemeans cooperating with said clutch operator adapted to disengage saidclutch regardless of the operation of either the automatic or suctionclutch engaging mechanism.

16. In combination with a clutch automatically engageable above apredetermined rotative speed, a suction clutch operator adapted topermit said clutch to engage regardless of the rotative speed andoperative to disengage said clutch at high degrees of suction when therotative speed is be low the predetermined speed, means for delaying themovement of said suction clutch operator from its clutch disengagingposition to its inactive position whereby to provide a predetermineddelay in clutch engagement suilicient toproperly pick up the load underextreme operating conditions, and manually operable means cooperatingwith said clutch operator adapted to disengage said clutch regardless ofthe operation of either the automatic or suction clutch engagingmechanism.

17. 'I'he combination with an internal combustion engine having anvintake manifold and an accelerator, of a clutch mechanism includingyback springs for holding said centrifugally confor effectingdisplacement of said pressure plate toward said driving member tocomplete clutch engagement, centrifugally controlled members operativeby said driving member and acting to effect displacement of saidpressure plate toward said driving member to complete clutch engagement,holdback springs for holding said centrifugally controlled members inretracted position at low speeds of the driving member but yieldable topermit said last named members to effect clutch engagement at highspeeds of the driving member, clutch release means, and a vacuum clutchcontrol operatively connected to said clutch release means and incommunication with said intake manifold for 4effecting lateraldisplacement of said centrifugally controlled members selectively toeffect clutch engagement by the clutch springs or by the centrifugallycontrolled members in response to the speeds of the driving member andthe vacuum condition in the intake manifold.

18. The combination with an internal combustion` engine having an intakemanifold, 'a carburetor communicating with the intake manifold, athrottle valve in said carburetor adjacent said intake manifold and anaccelerator operatively connected to said throttle valve, of clutchmech- 4 anism including driving and driven members,

trifugally controlled members operable by said driving member and actingto effect lateral displacement of said pressure plate toward saiddrivmember to complete such engagement, holdtrolled members in retractedposition at low speed of said driving member but yieldable to permitsaid last named members to effect clutch engagement at high speed ofthedriving member; clutchrelease means, a vacuum clutch control operativelyconnected to said clutch release means, means for establishingcommunication between the interior of the intake manifold at a point onthe intake manifold side of the throttle valve and the vacuumclutch-control for 'controlling the operation oi' the vacuum clutchcontrol by said acceleratorl 19. In an automatic clutch mechanism for aninternal combustion engine, driving and driven members mounted forengagement and disengagement, speed responsive means for forcing themem-bers into engagement, resilient means tending to force the membersinto engagement, a control element shiftable* by diierential pressuresand oprably connected to the clutch mechanism,

said control element being exposed to atmosvpheric pressure on one side,means connecting the engine intake manifold to the opposite side of saidcontrol elementto expose said opposite side to intake manifold pressurewhich varies with the speed of and torque transmitted by the engine, andmeans exercising a governing influence upon the pressure variations,whereby in response to certain pressure changes said control elementshifts so as to move the clutch members comparatively rapidly towarddisengaged condition against the action of the resilient means and uponcertain other pressure changes said control element shifts so that saidclutch members move at ERNEST E. WEMP.

